Fig. 5: Classification concept of soil microhabitats: large pores (Lp), substrate-rich small pores (SpRich), and substrate-poor small pores (SpPoor).
From: Composition and metabolism of microbial communities in soil pores
(1) The Lp habitats consist of large pores (>30 µm) that are formed and primarily occupied by roots or detritus, aka biopores, leading to high supply of C and nutrients, and O2 availability with temporarily variable moisture conditions. The bacterial communities in Lp are dominated by plant-residue decomposers and abundant predators, and have low potential for C sequestration because of intensive decomposition of organics. (2) The SpRich habitats consist of small pores (<10 µm) in rhizosphere and detritusphere, thus with high supply of C and nutrients but somewhat limited O2 and with a highly diverse bacterial community dominated by microbial-residue decomposers. The SpRich habitats have high potential for C sequestration because of high C input, fast microbial turnover, and close contact of microbial necromass with soil matrix. (3) The SpPoor habitats consist of small pores (<10 µm) in the bulk soil (far from roots or detritus), with limited C and nutrient resources and low O2 leading to the bacterial community of oligotrophic passive consumers. The SpPoor habitats have low potential for C sequestration because of low C input and slow microbial turnover. Detailed description of the hypothesized characteristics of the three habitats are provided in Table 1.
